1. Technical Field
This invention relates generally to avionic electronics and, more particularly, to an avionic communication system which integrates previously individualized communications components by allowing the detection of several avionic communication waveforms with a single article of digital hardware.
2. Discussion
The current configuration of avionic suites, or the electronics of the airplane, is that of single function articles of communications hardware, each individually designed to perform a single processing function such as navigation, friend/foe identification or voice communications. A main reason for utilizing a separate piece of hardware for each of these functions is that they are each performed using a different signal type having unique characteristics. For instance, signals such as those used to identify an aircraft as a friend or foe are pulsed sinusoids. In contrast, spread spectrum signals used for communication systems and for navigation are transmitted and received as PSK (Phase Shift Key) or FSK (Frequency Shift Key) modulated signals.
The modes of operation of interest in an exemplary military avionics system may include the following:
Mark XII Transponder and Mark XII Interrogator PA1 TACAN (Tactical Air Communication And Navigation) PA1 Mode S Transponder PA1 AN/ARC-164, AN/ARC-186, AN/ARC-199 PA1 VOR, ILS, MLS PA1 PLRS EPUU (Precision Location Report System, Enhanced Precision Location Report PA1 System User Unit) PA1 T-JTIDS (Time Division Multiple Access-Joint Tactical Information Distribution System) PA1 GPS (Global Positioning System)
The Mark XII Transponder mode allows an aircraft to receive interrogation waveforms made up of sequences of pulsed sinusoids from a Mark XII Interrogator. There are five modes of interrogation possible, commonly known as modes 1, 2, 3/A, C and 4. Each of these modes is represented by its own specific pattern of pulsed sinusoids as shown graphically in FIG. 1. The Mark XII Interrogator mode allows an aircraft to receive reply waveforms in response to previously transmitted pulsed sinusoid interrogations which are also made up of a sequence of pulsed sinusoids. There are two basic formats for the allowed pulsed sinusoid replies as shown graphically in FIG. 2. TACAN is a mode which allows navigation information to be obtained or supplied by an aircraft. This mode is likewise represented by patterns of pulsed sinusoids as shown in FIGS. 1 and 3.
The Mode S Transponder mode allows an aircraft to receive ATCRBS 3A and C interrogations, ATCRBS/Mode S All-Call interrogations and Mode S Interrogations. The first two of these types of interrogations are patterns of pulsed sinusoids as shown in FIG. 4. The third, Mode S, is a pulsed sinusoid pattern preamble followed by a DPSK (Differential Phase Shift Key) waveform containing the interrogation message, as illustrated by FIG. 5.
Various others of these modes are for signals in the UHF and VHF frequency range. The AN/ARC-164 mode allows an aircraft to receive a UHF AM signal and the AN/ARC-186 mode allows an aircraft to receive VHF AM or FM signals. The AN/ARC-199 mode allows an aircraft to receive HF AM or FM signals. VOR, ILS and MLS modes, used by aircraft as navigation and landing aides, allow an aircraft to receive various combinations of VHF and UHF signals that have relative navigation information modulated in either amplitude or frequency.
PLRS EPUU and T-JTIDS modes are used by an aircraft to receive and send tactical information to other aircraft on the same network. The information transferred in these modes is contained within MSK (Minimum Shift Key) modulated signals.
It is evident from the description of these various representative modes of interest that, in the past, as these modes were introduced, an existing radio could not process them due to an inherent lack of reconfiguration in a totally hardware implemented radio. Therefore, due to vast differences in these signal types, different receiver electronics were necessary for each.
However, the size, weight, performance, reliability and maintainability of each of these individual pieces of hardware has become very critical, especially in military applications. The need for individual hardware elements for the various avionic modes makes redundancy for fault tolerance and the provision of backup equipment almost impossible. Furthermore, enhancements must be provided individually to each article of hardware, making them both difficult and expensive. Existing avionic systems, made up of these various individual elements, have to be configured manually and therefore have low reliability with high maintainability.
It would, therefore, be desirable to integrate these various single function components into a multiple function single article of hardware in order to reduce hardware costs as well as the weight and size of the avionic suite. Integration of such system components would also facilitate redundancy and system enhancements.